title: Silencing DNA methyltransferase (DNMT) enhances glioma chemosensitivity.
abstract: Previously, we demonstrated that demethylation with 5-Aza-2'-deoxycytidine (5azadC) resulted in reduced levels of telomerase that led to telomere shortening, enhanced MGMT expression and enhanced chemosensitivity. Although the results were encouraging, the fact that 5azadC is highly toxic and nonspecific, thus is not favored as a therapeutic molecule. The aim of this research is to downregulate the DNA methyltransferase (DNMT1) gene using three sets of double-stranded RNA oligos designed to align different regions of DNMT1 sequence. Results showed the small-interfering RNA (siRNA) 1 and 3 demonstrated significant levels of silencing DNMT1 and hTERT transcription after 24-hour treatment (p = 0.01) and approximately 90% and 70% transcriptional downregulation of DNMT1 and hTERT, respectively after 48 hours. However, siRNA 2 downregulated DNMT1, hTERT, and MGMT in GOS-3 and U87-MG cells that was attributed to sequence homology between oligo 2 and MGMT complementary DNA. The siRNA-treated glioma cell lines GOS-3 and U87-MG were subjected to two chemotherapeutic agents; taxol and Temozolomide (TMZ). Results suggest that either a combination of siRNA 1 or 3 followed by taxol (2-6 muM) after 48 hours or a combination of siRNA 1 or 3 followed by TMZ (600-1000 microM) after 24 hours would be novel and effective glioma therapies.
authors.affiliation: Brain Tumour North West, Faculty of Science, University of Central Lancashire, Preston, UK. aashervington@uclan.ac.uk
authors.forename: Amal
authors.initials: A
authors.lastname: Shervington
authors.forename: Rahima
authors.initials: R
authors.lastname: Patel
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics*; D019175:DNA Methylation; D003606:Dacarbazine / Q000031:analogs & derivatives / Q000494:pharmacology; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D005910:Glioma / Q000188:drug therapy / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D017239:Paclitaxel / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D019098:Telomerase / Q000187:drug effects / Q000378:metabolism*; D000077204:Temozolomide
chemical_list: D018906:Antineoplastic Agents, Alkylating; D000972:Antineoplastic Agents, Phytogenic; D034741:RNA, Small Interfering; D003606:Dacarbazine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; D019098:Telomerase; D017239:Paclitaxel; D000077204:Temozolomide